There occasionally arises pains or tumors when a vein is partly clogged with a thrombus or the like. One method of treatment for such troubles is by the removal of thrombi through a thrombus-removing device which is inserted percutaneously. This method, however, involves a possibility of causing pulmonary embolism in the case where the thrombus which has entirely or partly peeled off a blood vessel wall reaches a lung together with blood flow. A common countermeasure to avoid this trouble is to use a thrombolytic agent before and after treatment and/or during treatment, or to remove by suction as many thrombi as possible during treatment. Such measures, however, still have the possibility that some peeled thrombi large enough to cause clinical problems reach the lung.
One of the known methods for avoiding pulmonary embolism involves the use of a filter to catch and collect thrombi flowing through the blood vessel. For example, U.S. Pat. No. 6,142,987 discloses a device which is composed of a long wire and a reticulate filter attached to the distal part of the wire, with the wire laying at the center of the filter.
Unfortunately, the wire is positioned along the center axis of the filer and hence the filter is liable to turn around the wire. This is true particularly in the case where a device is inserted into the blood vessel along the wire and the device is turned, the wire receives a revolving force, thereby causing the filter to turn. The result of the filter turning is a decrease in the filter's ability to catch thrombi and the like in the blood vessel. This in turn leads to an increased burden on the living body.